Several journeys around Orkney

I’ve been in the Orkney Islands for several days, departing from Scrabster (Near Thurso) with stays in St Margaret’s Hope, Kirkwall and somewhere between Finstown and Tingwall.

Total journey length including ferries, busses, walking and the world’s shortest commercial flight : 516 km.

More to follow.

GPS trails around Orkney
GPS trails around Orkney

Perseids meteor shower

I watched the meteor shower from the field at the Secret Nuclear Bunker where a group of us were camped doing radio stuff including bouncing signals off the ionized gas trail left by burned up meteors (meteor scatter).

I captured this time-lapse video which does include a few meteors as well as a pass by the ISS. The bright blob moving in from the left is the moon.

The circular trails are the stars moving across the sky around the pole star (not quite in frame)

De-capping ICs for fun and profit, but mostly fun.

Some time back, a friend @codfishcatfish was building a GPS disciplined oscillator for radio measurements. Part of the circuit uses a MAX232 device to interface the low voltage digital signals to a PC serial port. He found his cheap (from eBay) MAX232s got very hot and failed in use.

It was obvious the devices were fake, so I offered to tear one down to see what it really was, a cheap clone or a re-badged something else?

 

A couple of sacrificial fake ICs
A couple of sacrificial fake ICs

The standard technique to remove all the epoxy and metal to leave the bare silicon die is to use strong nitric acid. So I cut the legs off the chips, no point wasting acid dissolving those, and ground away some of the epoxy resin to speed up the dissolution.

ICs with legs and some of the epoxy package removed
ICs with legs and some of the epoxy package removed

Soaking the ICs for an hour in room temperature nitric acid had no discernible effect, so I heated up the acid. The reaction became very vigorous!

It took about 20 minutes to remove sufficient epoxy to see the silicon die – it also removed the lead-frame and bond-wires so there was no chance to test the ICs after de-capping.

 

Cruddy mess after the acid finishes its work
Cruddy mess after the acid finishes its work

 

After the acid had done its work the bare die was visible in both ICs
After the acid had done its work the bare die was visible in both ICs

The ICs were dried and the die removed by scraping away the carbonised epoxy with a scalpel. This done, the die could be examined under high magnification to see if it looked anything like a real MAX232 or I could see any other identifying features.

Bare die of fake MAX232
Bare die of fake MAX232

Comparison with a real MAX232 die proves these ICs are fake. The only identification I could find on the die is the following

Identification marks
Identification marks

So I’m non the wiser as to who actually made these, but the device does seem to show a general resemblance to the layout of a real MAX232 – they didn’t just program a micro-controller to do the job or something similar.

It was just a fun diversion and a chance to try something I’d wanted to do for a while. I might try to find some more interesting ICs to pull apart and take better images of.